Internal combustion engines operate under a wide range of temperatures including low temperature stop-and-go service as well as high temperature conditions produced by continuous high speed driving. Stop-and-go driving, particularly during cold, damp weather conditions, leads to the formation of sludge in the crankcase and in the oil passages of a gasoline or a diesel engine and deposits in the piston and cylinder, seriously limiting the ability of the crankcase oil to effectively lubricate the engine. In addition, the sludge with its entrapped water tends to contribute to rust formation in the engine. These problems tend to be aggravated by the manufacturer's lubrication service recommendations which specify extended oil drain intervals. Also diesel engines operate at a high temperatures and compression and frequently uses high sulfur fuels, generating excessive deposits on the piston and ring areas. Oils must be formulated with suitable dispersants and detergents to resist or remove such deposits.
It is known to employ nitrogen containing dispersants and/or detergents in the formulation of crankcase lubricating oil compositions. Many of the known dispersant/detergent compounds are based on the reaction of an alkenylsuccinic acid or anhydride with an amine or polyamine to produce an alkenylsuccinimide or an alkenylsuccinamic acid as determined by selected conditions of reaction.
It is also known to chlorinate alkenylsuccinic acid or anhydride prior to the reaction with an amine or polyamine in order to produce a reaction product in which a portion of the amine or polyamine is attached directly to the alkenyl radical of the alkenylsuccinic acid or anhydride. The thrust of many of these processes is to produce a product having a relatively high level of nitrogen in order to provide improved dispersancy in a crankcase lubricating oil composition.
With the introduction of four cylinder internal combustion engines which must operate at relatively higher engine speeds than conventional 6 and 8-cylinder engines in order to produce the required torque output, it has become increasingly difficult to provide a satisfactory dispersant lubricating oil composition. Thus, it is an object of this invention to provide a novel lubricating oil additive.
Another object is to provide a lubricating oil composition which can withstand the stresses imposed by modern internal combustion engines.